It should be of exceeding concern to the United States when barbarism typical of al Qaeda takes place just south of the border.

Mexican forces recently notched a big win against the drug cartels that have plunged much of the country into chaos, killing drug kingpin Arturo Beltran Leyva in a daring raid.

Ensign Malquisedet Angulo Cordova, a special-forces sailor who was killed in the battle, became an instant national hero.

But he wasn’t the only casualty: Leyva’s cartel took revenge last week by gunning down Cordova’s mother and three other family members — just hours after the sailor’s funeral.

“These contemptible events are proof of how unscrupulously organized crime operates, attacking innocent lives, and they can only strengthen us in our determination to banish this sing- ular cancer,” Mexico’s president, Felipe Calderon, said on Tuesday.

Let’s hope so.

The Mexican cartels may not have the sweeping global aims of Islamic terrorists, but they can be just as brutal — and their warlordism just as corrosive to civil society.

Judges, politicians and police who stand up to them face assassination — if they’re not already on the take. Federal soldiers involved in drug raids have taken to wearing masks to conceal their identities.

Inter-cartel violence has even seeped into US border states.

Meanwhile, Calderon’s three-year war on the cartels has met with mixed success. Still, bravo to him for keeping up the fight.

No country that backs down in the face of terror is long for this world.

And, needless to say, further chaos in Mexico could be disastrous for its northern neighbor.